Notes: Growing on a lawn under pine & some unidentified deciduous ornamental trees, oak was across the street. Radish odor.

This was on the same lawn as the Hebeloma in obs 121683, but they both occupied opposite sides with some empty space in between. These were distinctly smaller and paler, the basidia also were noticeably smaller, but I have not measured them yet for either collection…

Comments

from me, I’m afraid. You are doing a great job with documentation here, but the Hebelomas are poorly known both in North America and in Europe. Routine ID:s of all species with drops on the gill edge as crustuliniforme doesn’t help much either :-)

In Mycologia 92(2) is a preliminary study of the Hebeloma crustuliniforme complex in Europe.
There you can find a phylogram where the known european names (crustuliniforme, hiemale, helodes, pusillum and lutense) are found both here and there, and it discloses the problems even experts have, trying to ID them.. H. populinum is another name that probably belongs in that group.

Of the mentioned species above, lutense and populinum have distinctly dextrinoid spores. H. crustuliniforme sensu stricto is not supposed to have it.

Would the dextrinoid spores rule out H. crustuliniforme? Many spores showed this reaction, not only the few I managed to get a useful picture from, many more did not turn in the time I watched them. With the micro info you provide, I’m not sure the cheilocystidia would match either of those other species, I don’t recall and didn’t record any thick walled ones. They were close to the other Hebeloma I scoped from this yard, I don’t think they are the same though.

is a terribly difficult genus..!
At first sight, this could pass as crustuliniforme too, but we don’t really know how many species that exist around it. Other smaller species that have been described and could look similar are hiemale and helodes, but I wouldn’t be surprised if you have some other species in California.

H. helodes has cheilocystidia with a thick-walled apex, but slightly smaller spores than this one.
H. hiemale is described with a larger variation in both cap and spore size and cheilocystidia often with a thick-walled median part and swollen right above the base – not quite as broad as these, not over 8 microns according to the description I have.
Both of these are described to have indistinctly dextrinoid spores.